package main

/*
算数：+ - * / %
位：& | ^ &^ << >>
逻辑：== != < <= > >= && || ！
chan: <- ->

优先级 	运算符
 7 		^ !
 6 		* / % << >> & &^
 5 		+ - | ^
 4 		== != < <= >= >
 3 		<-
 2 		&&
 1 		||
*/
